Alterations in adrenal steroid secretion and/or morphology are observed in both experimental and spontaneous hypertension in the rat. It is our objective to completely characterize these alterations qualitatively and quantitatively over the time-course of development of hypertension. Evidence for a potent, pituitary dependent salt retaining factor ("SRF") (GAUNT) being secreted immediately following adrenal enucleation in the course of the development of adrenal regeneration hypertension has also been obtained in this laboratory. "SRF" will be isolated and identified and its role in the genesis of hypertension assessed. The possibility that "SRF" has wide biological significance and that such a substance may play a role in low renin hypertension in man is intriguing.